1. Field of the Invention
My present invention relates to improvements in disposable face masks.
2. Description of the Prior Art
Face masks have widely been used to filter particulate matter from contaminated air. Otherwise such particulate matter, which may consist of either solid or liquid particles, may be inhaled and then transmitted to the upper respiratory tract or to a person's lungs, possibly triggering emphysema or a number of other respiratory conditions or diseases. Consequently, such masks fulfill a vital role in a wide variety of industrial and consumer applications.
Inexpensive face masks which are designed to be disposed of after a limited number of uses have enjoyed wide popularity. Such masks are commonly molded from a sheet of fibrous material into a configuration adapted to substantially seal against the face around the periphery of a mask. These masks must be constructed to accommodate a wide variety of facial sizes and configurations, and therefore the periphery does not always tightly engage and seal against the skin. Consequently, the wearer may be exposed to contaminated air leaking between the periphery of the mask and the face.
The problem of air leakage at the outer periphery is often aggravated after the mask is initially worn. When the fibers of the mask start to fill with particulate matter, the mask offers a greater resistance to air flow and subsequently a greater tendency for air leakage around the periphery is created. Unfortunately, the person using the mask is often unaware of this phenomena, because the overall resistance to air flow has remained substantially the same.
Attempts to eliminate air leakage in the nasal area have been generally unsuccessful. Occasionally, a small strip of U-shaped formable material such as metal has been secured to the mask over nose bridge area thereof and provided with leg portions which extend along both sides of the nose, with the intention that the strips will be conformably pressed against the nose by the wearer and thereafter cause the interior surface of the mask to provide a more effective seal between the interior of the mask and the ambient atmosphere. However, the use of such formable materials is subject to many disadvantages. The user may forget to press the strip against the side of his nose. Alternatively, the formable strip may become disfigured during use. Also, it may be impossible to reform material after several refittings of the respirator. Additionally, in order to allow ready manual forming of the strip as desired, such material must of necessity be relatively soft and have little memory. As a consequence, there was a tendency for such material to give and the U-shape to open, thus releasing the sealing pressure of the mask against the user's nose.
Similarly, previous face masks have not provided an adequate seal at the chin area of the face. Most respirators depend totally on the peripheral interior of the generally cup-shaped mask body of the respirator to prevent entrance of contaminated air around the chin. Again, because of the wide variety of facial sizes and structures, prior masks have often leaked in the chin area because the mask periphery did not properly match the general shape of the user's face.
Other respirators have used a complex shaped rounded seal, or a gas or liquid filled seal around the periphery of the mask. However, these seals are not suitable for disposable respirators which consist almost entirely of a molded sheet of fibrous material. As a result, disposable masks are often manufactured with no adequate peripheral chin seal, thereby exposing the user to possible inhalation of contaminated air.